Dear Lifehacker,
I recently jumped on the Android bandwagon and I've found myself frustrated by the silliest of things—wallpaper. What is the deal with Android wallpaper and why don't images sized to fit the resolution of my screen work properly?

I feel really silly sending this question in since I'm sure the answer is extremely elementary. I just can't figure out why images that are perfectly cropped for my Android phone's screen resolution don't load properly. The gallery tool in Android insists that I crop the image, it rotates them strangely, and the end result is a pixelated and blurry mess—definitely not the image I had carefully cropped and saved to my SD card. Help!

Sincerely,
Blurry Wallpaper in Baltimore

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Dear Blurry Wallpaper,

Don't worry, it's not a silly question! Android handles wallpaper in a unique way and if you're unaware of the method behind the madness you'll find yourself extremely frustrated. Many an Android user has checked the resolution of their phone, hit up the web to grab perfectly cropped wallpaper, and then been disappointed when Android forced them to crop it, it looked blurry, and it didn't fit the screen right.

The secret to understanding Android wallpaper requirements is to understand how Android handles wallpaper. Unlike many smartphones, like the iPhone, Android does not have fixed wallpaper. On the iPhone, for example, if you set a picture as your background then no matter how many times you swipe along the applications screen that image stays in the background. Android phones, however, span the wallpaper across all three of the home screens. It isn't simply the resolution width of the home screen multiplied by three, however. The wallpaper is "panned" as you move between screens, not just spanned across all three. The wallpaper thus needs to be 2 times the width of the screen resolution, not 3 times. Check out the images below to get an idea of how this works. Wallpaper by smjfosho.

The first image is a 640x480 wallpaper, the right size for an Android phone that has a 320x480 resolution screen.

The second image is the original wallpaper spliced apart to show how Android "sees" it, when displaying it across the home screens. Notice how the medallion from the center of the image appears, partially, on both the left and right home screens.

That's why when you put an image on your SD card, sized perfectly to the resolution of the screen, Android forces you to crop it. It's trying to turn your 3:2 image into a 3:4 image to fit the way Android handles the home screen wallpaper. The perfect wallpaper, no cropping necessary, is 1*height by 2*width where the height and width value are the hardware screen resolution values of your phone.

For a quick and dirty source of wallpapers, hit up Google Images and set the "Exactly..." parameters to the wallpaper resolution required for your phone like these 640x480 abstract wallpapers. Happy customizing!